Biology

Carries food from the mouth to the stomach

Incorporating absorbed molecules into body tissues

The breaking down of large molecules into smaller ones by the addition of water

General term given to enzymes that slip up molecules by hydrolysis

One of many small molecules that combine to form a larger one known as a polymer

Large molecule made up of repeating smaler molecules

C_nH_2nO_n

Add equal volume of Benedict's reagent to the food sample and heat in a gently boiling water bathfor 5 minutes and if a red-brown precipitate is formed the sample is a reducing sugar

Chemical process of combining  two molecules to form a more complex one and water is generally lost

Glycosidic bond

Alpha glucose and alpha glucose

Alpha glucose and fructose

Alpha glucose and galactose

• Do the Benedicts test and if it's negative do the following in a separate test tube:
• Add dilute hydocholoric acid to the food sample and place in a gently boiling water bath for 5 minutes
• Slowly add sodium hydrogencarbonate solution to the test tube to neutralise the acid
• Test with pH paper for an alkaline solution
• Re-test by adding Benedicts solution and placing in the gently boiling water bath for 5 minutes and if a non-reducing sugar is present an orange-brown colour will show

Add 2 drops of iodine solution to 2cm³ of the food sample and if starch is present it will turn a blue-black colour

Permanent change due to the unravelling of the structure of a protein as a result of factors such as temperature and pH

• The milk lowers the water potential of the small intestine
• So the water moves from the epithelial cells to the  lumen of the small intestine due to the concentration gradient by osmosis
• This then causes the faeces to become overly watery which leads to diarrhoea

Process of removing faeces

Maltase, sucrase and lactase

Process of joining many amino acids to form a polypeptide

Peptide bond

Amine group, carboxyl group and the R group

NH₂

COOH

Sequence and number of amino acids joined by peptide bonds

Folding of chains of amino acids into an alpha helix or beta pleated sheet by the formation of H bonds

Where the secondary structure is further folded to form a coiled 3D structure. The bonds involved as H bonds, ionic bonds and covalent bonds (disulfide bonds)

Combination of more than one polypeptide

The energy required to bring about a reaction

A group of amino acids that makes up a region of an enzyme into which a substrate fits in order to catalyse a reaction

• The inhibitor is similar shape to the substrate so can bind at the active site
• The higher the substrate concentration the less affect the inhibitor has

• Inhibitor is a completly different shape to the substrate to binds to a different site that isn't the active site
• When it binds the active site changes shape no the substrate can't fit in so no enzyme substate complex can be formed

Drawing, actual, magnification and units

The minimum distance apart two objects can be in order for them to appear as separate items

Process where cells are broken up and the different organelles they contain are separated out

• Cold - to reduce enzyme activity that may break down the organlles
• Isotonic - to prevent organelles bursting or shrinking due to osmotic gain or loss; as it has the same water potential as the tissue
• Buffered - to maintain a constant pH

When cells are broken up by the homegeniser (blender) to separate out the organelles. The resultant fluid is known as the homogenate and this is then filtered out to remove complete cells and large pieces of debris

The process by which the fragments of the homegenate are separate in a machine called a ultracentrifuge. The organelles are removed heaviest first: nucleus, mitochondria, lysosomes then ribosomes

• Advantages: short wavelength, high resolution
• Limitations: needs to be in a vacuum so living specimens can't be observed, black and white images, specimen needs to be very thin, needs to be prepared so artefacts may appear

• Advantages: short wavelength, 3D images can be produced, specimens don'tneed to be that thin as electrons don't penetrate
• Limitations: lower resolution than TEM and living specimens can't be used

Epithelial cells of the small intestine

Bacteria such as vibrio cholerae

• Act as the control centre of the cell
• Hold genetic material of the cell in the form of DNA or chromosomes
• Manufacture ribosomal RNA and ribosomes

• 1 - 10 micrometres
• Double membrane - controls entry and exit of material
• Cristae - extensions of inner membrane, provide a larger surface area for respiration
• Matrix - control production of their own proteins, enzymes for respiration found in the matrix

• Site for aerobic respiration
• Production of ATP

Found in cells that have a high metabolic activity and use a lot of ATP e.g.muscles

• Provide a large surface area for the synthesis of proteins and glycoproteins
• Provide a pathway for the transport of materials such a proteins throughout the cell

e.g. liver and secretory cells such as the epithelial cells of small intestine

• Synthesis, store and transport lipids
• Synthesis, store and transport carbohydrates

• Add carbohydrates to proteins to form glycoproteins
• Produce secretory enzymes
• Secrete carbohydrates, such as those used to make the cell walls in plants
• Transport, modify and store lipids
• Form lysosomes

E.g. loads found in secretory cells such as epithelial cells

• Break down of foreign materials brought into the cell (phagocytosis)
• Release enzymes to the outside of the cell (exocytosis) in order to destory surrounding material
• Digest worn out organelles (autophagy)
• Completely break down cells after they have dies (autolysis)

Mechanism by which cells engulf particles particles to form a vesticle or a vacuole

An individual lipid molecule made up of a glycerol molecule and three fatty acids

• Energy source - lipids provide more than twice the energy as carbohydrates
• Waterproofing - insoluble in water
• Insulation - fats are slow conductors of heat and help to retain body hear
• Protection - stored around delicate organs such as the kidneys

• A fatty acid where there are no double bonds between the carbon atoms
• 

A fatty acid in which there is one double bond between the carbon atoms

• A fatty acid in which there is more than one double bond between carbon atoms
• 

• Phospholipid - glycerold molecule andd 2 fatty acids
• Triglyceride - glycerol and 3 fatty acids

• Add an alcohol such as ethanol to the sample
• add water and shake gently
• A cloudy-white colour indicates the presense of lipids

• Allow lipid-soluble substance to enter and leave the cell
• Prevent water-soluble substances entering and leaving
• Make the membrane flexible

Proteins that are on the surface or are only part way through the membrance

Completely span the membrance from one side to the other

• Provide structural support
• Acts as carried for water-soluble substances
• Allow active transport by forming ion channels
• Help cells adhere together
• Act as receptors e.g. for hormones

• Fluid - as the membrane is constantly moving because of the flexible structure
• Mosaic - proteins are embedded in the phospholipd bilayer and vary in shape and size

The net movement of molecules or ions from a region of high concentration ot a region of lower concentration

Diffusion through a carrier protein from a region of high concentration to low concentration

Surface area x concentration difference

              Diffusion distance

Passage of water molecules from a region of high water potential to a region of lower water potential through a partiall permeable membrane

Strong solution (low water concentration)

Weak solution (high water concentration)

• Hypertonic (low wp) - leaves cell so shrinks 
• Hypotonic (high wp) - enters cell so swells and bursts

• Hypertonic (low wp) - leaves cell so becomes plasmolysed/crenated
• Hypotonic (high wp) - enters cell so becomes turgid

The movement of molecules or ions into or out of a cell from a region of low concentration to a region of high concentration using energy and carrier molecule

• Nucleus and nucleolus
• Chromosomes
• Membrane-bounded organlles (mitochondria etc)
• Chloroplasts
• ER, golgi body and lysosomes
• If it has a cell wall it's made of cellulose

Bacteria such as vibrio cholerae

Epithelial cells, plant cells and animals cells

• Water - for rehydration
• Sodium - replace lost ions and make use of sodium-glucose pumps
• Glucose - Encourage uptake of sodium and provides energy
• Potassium - replace lost ions and stimulate appetite